1. Field of the Invention
The present invention relates to a light emitting device including a light emitting element in which phosphorescence or fluorescence can be obtained by applying an electric field to an element provided with a film containing an organic compound (hereinafter referred to as an “organic compound layer”) between a pair of electrodes. The present invention further relates to a method of manufacturing thereof. In this specification, the light emitting device indicates an image display device, a light emitting device, or a light source (including a lighting equipment). In addition, examples of the light emitting device also include a module with a connector such as a flexible printed circuit (FPC), a tape automated bonding (TAB) tape, and a tape carrier package (TCP) attached to a light emitting device, a module with a printed circuit board provided at the end of a TAB tape or a TCP, and a module with an integrated circuit (IC) directly mounted on a light emitting element by a chip on glass (COG) method. The present invention further relates to a method of manufacturing the light emitting device.
2. Description of the Related Art
In recent years, researches on a light emitting device comprising an EL element as a self-luminous light emitting element has been activated. The light emitting device is also referred to as an organic EL display or an organic light emitting diode. The light emitting devices have characteristics such as high response speed which is suitable for displaying moving images, low voltage drive, and low power consumption drive. Therefore, the light emitting devices has recently been attracting attention as a next-generation displays including new-generation cellular phones, personal digital assistants (PDA), and the like.
The EL element includes a layer containing an organic compound in which electroluminescence can be obtained by applying electric field thereto, an anode, and a cathode. The electroluminescence in the organic compound includes light emission (fluorescence) upon returning form a singlet excited state to a ground state and light emission (phosphorescence) upon returning from the triplet excited state to the ground state. Either or both types of the luminescence can be used for the light emitting device manufactured by a film formation device and a film formation method according to the present invention.
As different from a liquid crystal display device, the light emitting device has characteristics in that they have no problem with the viewing angle because it is a self-luminous type. More specifically, the light emitting device is more suitable for displays used in outdoors than the liquid crystal display. Various forms for use have been proposed.
In this specification, the light emitting element including the cathode, an EL layer and the anode is referred to as the EL element. The EL element has two types: the system in which the EL layer is formed between two kinds of stripe electrodes disposed orthogonal to each other (simple matrix system), and the system in which the EL layer is formed between an opposite electrode and pixel electrodes connected to TFTs and arranged in matrix (active matrix system). However, when the pixel density is increased, the active matrix system in which a switch is provided for each pixel (or a dot) is considered to be advantageous because it is available for low voltage drive as compared with the simple matrix system.
Conventionally, there has been an electronic equipment in which a plurality of different panels is formed. For instance, a lap-top computer is provided with a monochromatic reflection type liquid crystal panel for displaying simple display such as a power source level, and a battery level in addition to a main display screen panel (a transmission type liquid crystal panel for full-color display).